Sonos and Android together

[Android Central Question]

Thanks in advance I saw a vid by Phil and it mentioned Sonos w/ Android. It was simple, yet quite confusing going into the Sonos app. (I have the very simpe Home Max)

Could you explain the difference in why you needed the app, and what the difference in that and 2 other videos showing Sonos 5 with Google mini with the Chromecast audio plugged in between the previous 2. And then all they did was, after connecting the wire from Chromecast to the Aux, they selected on the app, something to the effect "once something plays while that jack has that in it, play thru the Sonos 5"

Thanks if you are able to help

Eric